Early intake valve closing and intake manifold pressure control

ABSTRACT

Systems, apparatus, and methods are disclosed that include an internal combustion engine having a plurality of cylinders and controlling the intake manifold pressure during early intake valve opening to reduce or prevent oil consumption.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 16/657,068 filed on Oct. 18, 2019, which isincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to an internal combustion engine includingmultiple cylinders, and more particularly to controlling intake manifoldpressure in conjunction with early intake valve closing of one or morecylinders.

BACKGROUND

The cylinders in an internal combustion engine can be operated withMiller cycling for efficiency improvements and NOx reduction. This maybe accomplished by late intake valve closing or early intake valveclosing. Late intake valve closing is typically employed due tooperational challenges with early intake valve closing.

For example, early intake valve closing significantly before bottom deadcenter of the piston causes the pressure in the cylinder to reduce asthe volume is increased. Depending on the intake manifold pressure, thein-cylinder pressure at bottom dead center can drop below crankcasepressure, which could allow oil to be pulled past the piston rings andinto the combustion chamber. The earlier the intake valve closing beforebottom dead center, the greater the concern. Therefore, furtherimprovements are needed if early intake valve closing is to be employedfor Miller cycle operation of an internal combustion engine.

SUMMARY

Embodiments include unique systems, apparatus, and methods that includea multi-cylinder internal combustion engine configured to operate withearly intake valve closing. In one embodiment, the engine includes a VGTthat is used to increase intake manifold pressure during conditions inwhich the in-cylinder pressure can drop below a crankcase pressure, thusreducing or preventing oil consumption during Miller cycling using earlyintake valve closing. A controller may be configured to receive one ormore inputs associated with an in-cylinder pressure and to controloperation of the VGT to increase intake manifold pressure when thein-cylinder pressure is determined and/or predicted to drop belowcrankcase pressure.

In one embodiment, the intake manifold pressure is increased duringconditions in which the in-cylinder pressure can drop below a crankcasepressure, thus reducing or preventing oil consumption during Millercycling using early intake valve closing. A controller may be configuredto receive one or more inputs associated with an in-cylinder pressureand to control operation of the engine to increase intake manifoldpressure when the in-cylinder pressure is determined and/or predicted todrop below crankcase pressure. The intake manifold pressure could beincrease by, for example, operating of an exhaust gas recirculation(EGR) pump, bypassing a low pressure turbine of a two stageturbocharger, bleeding air from another location such as the brakes,and/or an electric compressor in the intake system.

This summary is provided to introduce a selection of concepts that arefurther described below in the illustrative embodiments. This summary isnot intended to identify key or essential features of the claimedsubject matter, nor is it intended to be used as an aid in limiting thescope of the claimed subject matter. Further embodiments, forms,objects, features, advantages, aspects, and benefits shall becomeapparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of one embodiment of an internalcombustion engine system including a VGT.

FIG. 2 is a schematic depiction of an example of a cylinder of theinternal combustion engine of FIG. 1.

FIG. 3 is a flow diagram of a procedure for VGT operation of the systemof FIG. 1 in response to in-cylinder pressure and crankcase pressure.

FIG. 4 is a schematic depiction of one embodiment of an internalcombustion engine system including means for increasing an intakemanifold pressure.

FIG. 5 is a flow diagram of a procedure for operation of the system ofFIG. 4 in response to in-cylinder pressure and crankcase pressure.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, any alterations and further modificationsin the illustrated embodiments, and any further applications of theprinciples of the invention as illustrated therein as would normallyoccur to one skilled in the art to which the invention relates arecontemplated herein.

Referring to FIG. 1, a system 100 includes an engine 102 fluidly coupledto an aftertreatment system 104. The system 100 may further includes atransmission (not shown) coupled to the engine 102, which may be a partof a powertrain for propelling a vehicle driven by engine 102 viawheels. Other embodiments contemplate that system 100 is a marineapplication, locomotive application, part of a genset for powering agenerator, or other motive or non-motive application. The engine 102 maybe any type of internal combustion engine capable of operating with aMiller cycle, including at least a diesel, gasoline, natural gas engine,and/or combinations thereof.

In certain embodiments, the engine 102 includes a lean combustion enginesuch as a lean burn gasoline engine or a diesel cycle engine. In certainembodiments, the engine 102 may be any engine type producing emissionsthat may include an exhaust gas recirculation (EGR) system, for exampleto reduce NO_(x) emissions from the engine 102. In the illustratedembodiment of FIG. 1, the system 100 includes an engine 102 having anin-line 6-cylinder arrangement for illustration purposes. However,V-shaped arrangements and other any number of cylinders with V-shapedarrangements, multiple cylinder bank arrangements, and other in-linearrangements are also contemplated.

Referring further to FIG. 2, a typical multi-cylinder engine 102 has anengine block 106 with multiple cylinders 108 each with a combustionchamber 156 housing a piston 150 that is operably attached to acrankshaft 152. There is also at least one intake valve 160 and at leastone exhaust valve 162 that allow passage of air into and out of eachcylinder 108 from an intake manifold 110 to an exhaust manifold 112. Thetypical engine 102 operates on a four-stroke cycle that sequentiallyincludes an air intake stroke, a compression stroke, a power stroke, andan exhaust stroke for the piston of each cylinder. As used herein, onecycle of the cylinder 108 or engine 102 occurs at the completion ofthese four strokes.

One embodiment of the cylinder 108 includes piston 150 housed incombustion chamber 156 and operably attached to crankshaft 152, which isrotated by reciprocal movement of piston 150 in combustion chamber 156.Within a cylinder head 154 associated with the cylinder 108, there is atleast one intake valve 160, at least one exhaust valve 162 and a fuelinjector 164 that provides fuel to combustion chamber 156 between thepiston 150 and the cylinder head 154. In other embodiments, fuel can beprovided to combustion chamber 156 by port injection, or by injection inthe intake system, upstream of combustion chamber 156.

The term “four-stroke” herein means the following four strokes—intake,compression, power, and exhaust—that the piston 150 completes during twoseparate revolutions of the engine's crankshaft 152. A stroke beginseither at top dead center (TDC), when the piston 150 is at the top ofcylinder head 154 of the cylinder 108, or at bottom dead center (BDC),when the piston 150 has reached its lowest point in the cylinder 108.

During the intake stroke, the piston 150 descends away from cylinderhead 154 of the cylinder 108 to a bottom (not shown) of the cylinder108, thereby reducing the pressure in the combustion chamber 156 of thecylinder 108. In the instance where the engine 102 is a diesel engine, acombustion charge is created in the combustion chamber 156 by an intakeof air through the intake valve 160 when the intake valve 160 is opened.

During the compression stroke, both the intake valve 160 and the exhaustvalve 162 are closed, the piston 150 returns toward TDC and fuel isinjected near TDC in the compressed air in a main injection event, andthe compressed fuel-air mixture ignites in the combustion chamber 156after a short delay. In the instance where the engine 102 is a dieselengine, this compression results in the combustion charge being ignited.The ignition of the air and fuel causes a rapid increase in pressure inthe combustion chamber 156, which is applied to the piston 150 duringits power stroke toward BDC. Combustion phasing in combustion chamber156 is calibrated so that the increase in pressure in combustion chamber156 pushes piston 150, providing a net positive in the force/work/powerof piston 150.

During the exhaust stroke, the piston 150 is returned toward TDC whilethe exhaust valve 162 is open. This action discharges the burnt productsof the combustion of the fuel in the combustion chamber 156 and expelsthe spent fuel-air mixture (exhaust gas) out through the exhaust valve162.

The ambient air flow 116 provides intake air that flows through intakemanifold 110 before reaching the intake valve 160. The intake passagemay be connected to a compressor of a VGT 120, a charge air cooler (CAC)122, and an optional intake air throttle (not shown). The intake air canbe purified by an air cleaner (not shown), compressed by the compressor,and then aspirated into the combustion chamber 156.

The exhaust gas flows out from the combustion chamber 156 into anexhaust system 144 that includes an exhaust passage 142 extending fromexhaust manifold 112. The exhaust passage 142 is connected to a turbineof VGT 120 and to an exhaust gas recirculation (EGR) system 130. Exhaustgas from the turbine of VGT 120 then flows into aftertreatment system104 that includes one or more aftertreatment devices. The aftertreatmentsystem 104 may include any type of aftertreatment components known inthe art, including catalytic and/or filtration components. Exampleaftertreatment components may include, without limitation, oxidationcatalysts (e.g., a diesel oxidation catalyst (“DOC”), NO_(x) treatmentcomponents (e.g., three-way catalyst, lean NOx catalyst, SCR catalyst,etc.), a filtration component (either catalyzed or uncatalyzed, e.g., adiesel particulate filter (“DPF”), and a cleanup catalyst (e.g., anammonia oxidation catalyst).

The system 100 includes VGT 120 connected to exhaust manifold 112. A VGT120 may include movable vanes, but the VGT 120 can also be a variablenozzle turbine having a movable wall instead of movable vanes. VGT 120includes a turbine that receives exhaust flow and a compressor thatreceives ambient air flow 116. The compressor compresses the ambient airand provides it to CAC 122 which is connected to intake manifold 110.The exhaust manifold 112 is also connected to EGR system 130 thatincludes an EGR valve 132 and an EGR cooler 134. EGR system 130 isoperable to provide an EGR flow that combines with an intake flow at aposition upstream of intake manifold 110. Intake manifold 110 provides acharge flow including the intake flow and, if provided, the EGR flow tocylinders 108.

System 100 further includes a fuel system (not shown) that is operableto provide fuel from a fuel storage source, such as a fuel tank, tocylinders 108. A plurality of fuel injectors can be provided, at leastone per cylinder such as shown with injector 164, to inject fuel intoeach cylinder 108 in response to a fueling command from a controller140. In one embodiment, the fuel injectors are direct injectors. Itshould be understood that any suitable fuel system is contemplated.

In operation, the intake valve 160 and/or exhaust valve 162 may be openand/or closed by a valve operating mechanism 170, such as a cam shafthaving cam lobes that are connected to the intake valve 160 and/orexhaust valve 162 with any suitable valve operating mechanism 170 knownin the art. In one embodiment, the valve opening mechanism 170 isoperated to so that intake valve 160 is closed early during the intakestroke, such as before bottom dead center of piston 150 during theintake stroke, to provide Miller cycling benefits.

The controller 140 is connected to a plurality of sensors shownschematically as sensors 180, 182, 184. The sensors may be physical orvirtual sensors and include, but are not limited to, an intake manifoldpressure sensor 182 to detect, estimate, or sense intake manifoldpressure; engine sensor or sensors 182 to detect, estimate or senseengine conditions such as crankcase pressure; and cylinder sensor orsensors 184 which detect, sense, or estimate in-cylinder pressure in oneor more cylinder 108, cam shaft position (intake and/or exhaust), intakevalve closing angle, and/or volume changes in the cylinder betweenintake valve closing and bottom dead center. Sensors may also beprovided for vehicle speed, vehicle acceleration, engine position,engine speed, mass air flow into the manifold, engine temperature, airtemperature barometric pressure, EGR amount, VGT position, torquedemand, gear position, etc.

In certain embodiments, the controller 140 is structured or configuredto perform certain operations to control operations of engine 102. Incertain embodiments, the controller 140 forms a portion of a processingsubsystem including one or more computing devices having memory,processing, and communication hardware. The controller 140 may be asingle device or a distributed device, and the functions of thecontroller 140 may be performed by hardware or software. The controller140 may be included within, partially included within, or completelyseparated from an engine controller (not shown). The controller 140 isin communication with any sensor or actuator throughout the system 100,including through direct communication, communication over a datalink,and/or through communication with other controllers or portions of theprocessing subsystem that provide sensor and/or actuator information tothe controller 140.

In certain embodiments, the controller 140 is described as functionallyexecuting certain operations. The descriptions herein including thecontroller operations emphasizes the structural independence of thecontroller, and illustrates one grouping of operations andresponsibilities of the controller. Other groupings that execute similaroverall operations are understood within the scope of the presentapplication. Aspects of the controller may be implemented in hardwareand/or by a computer executing instructions stored in non-transientmemory on one or more computer readable media, and the controller may bedistributed across various hardware or computer based components.

Example and non-limiting controller implementation elements includesensors providing any value determined herein, sensors providing anyvalue that is a precursor to a value determined herein, datalink and/ornetwork hardware including communication chips, oscillating crystals,communication links, cables, twisted pair wiring, coaxial wiring,shielded wiring, transmitters, receivers, and/or transceivers, logiccircuits, hard-wired logic circuits, reconfigurable logic circuits in aparticular non-transient state configured according to the modulespecification, any actuator including at least an electrical, hydraulic,or pneumatic actuator, a solenoid, an op-amp, analog control elements(springs, filters, integrators, adders, dividers, gain elements), and/ordigital control elements.

The listing herein of specific implementation elements is not limiting,and any implementation element for any controller described herein thatwould be understood by one of skill in the art is contemplated herein.The controller or controllers herein, once the operations are described,are capable of numerous hardware and/or computer based implementations,many of the specific implementations of which involve mechanical stepsfor one of skill in the art having the benefit of the disclosures hereinand the understanding of the operations of the controllers provided bythe present disclosure.

Certain operations described herein include operations to interpret ordetermine one or more parameters. Interpreting or determining, asutilized herein, includes receiving values by any method known in theart, including at least receiving values from a datalink or networkcommunication, receiving an electronic signal (e.g. a voltage,frequency, current, or PWM signal) indicative of the value, receiving asoftware parameter indicative of the value, reading the value from amemory location on a non-transient computer readable storage medium,receiving the value as a run-time parameter by any means known in theart, and/or by receiving a value by which the interpreted parameter canbe calculated, and/or by referencing a default value that is interpretedto be the parameter value.

Certain systems are described following, and include examples ofcontroller operations in various contexts of the present disclosure. Theoperation of the engine 102, valve operating mechanism 170, and VGT 120is controlled by the controller 140 in response to engine operatingconditions sensed by the sensors represented by sensor(s) 180, 182, 184.In certain embodiments, the controller 140 interprets or determines acylinder pressure of one or more cylinders 108 is less than a crankcasepressure of engine 102, and in response thereto commands the VGT 120, ormeans other than VGT 120 disclosed herein as further described below, toincrease the intake manifold pressure. The command to increase theintake manifold pressure can include closing the VGT 120 or opening theVGT 120, depending on the current position of the VGT 120. It is alsocontemplated the command to increase intake manifold pressure includescommands to increase energy to the turbine, such as by delayed injectiontiming or lowering fuel rail pressure.

Referring now to FIG. 3, there is shown a procedure 300 for operatingsystem 100. Procedure 300 includes a conditional 302 to determine if thepressure in one or more cylinders 108 at bottom dead center of piston150 is less than a crankcase pressure of engine 102. In order to makethis determination, procedure 300 includes an operation 304 to detect,estimate, or sense the crankcase pressure, such as with sensor 182.Procedure 300 also includes an operation 306 to make a prediction of thepressure in cylinder 108 at bottom dead center of the piston 150. Thedeterminations from operations 304 and 306 are input to conditional 302to make the determination of conditional 302.

In one embodiment, operation 306 includes three different inputs todetermine the prediction or estimate of cylinder pressure at bottom deadcenter of piston 150 during the intake stoke of piston 150. One input308 includes the intake valve 160 closing angle, such as the crank angleof the crankshaft 152 when the intake valve 160 is closed. Procedure 300includes a second input 310 that includes a determination of a volumechange in the cylinder 108 between the intake valve 160 closing andbottom dead center of the piston 150. Procedure 300 includes a thirdinput 312 of the intake manifold pressure of intake manifold 110, suchas from sensor 180. Inputs 308, 310, 312 are used to make an estimate ofthe in-cylinder pressure at bottom dead center of piston 150 during theintake stroke at operation 306.

Returning to conditional 302, if the cylinder pressure at bottom deadcenter of piston 150 is not less than the crankcase pressure of engine102, then conditional 302 is NO and an oil consumption issue is notpresent. Procedure 300 continues to monitor crankcase pressure andin-cylinder pressure at bottom dead center. If conditional 302 is YES,then procedure 300 continues at operation 314 to command the VGT 120 toincrease the pressure at intake manifold 110, which will prevent orreduce oil blow by from the crankcase into the combustion chambers ofcylinders 108. Typically, the command includes causing the VGT inlet ofVGT 120 to modulate by closing or reducing the inlet size to increaseintake manifold pressure. However, if the inlet is already mostlyclosed, and turbine efficiency would decrease when the inlet is closedfurther such as by reducing airflow, then the VGT 120 may be opened atoperation 314. It is also contemplated the command to increase intakemanifold pressure can increase energy to the turbine by other means,such as by delayed injection timing or lowering fuel rail pressure.

Referring to FIG. 4, there is shown another embodiment system 400 thatis similar to system 100, and may include all or part of the elements ofsystem 100 as discussed above. For example, system 400 as shown includesan engine 402 with one or more cylinders, like cylinders 108 discussedabove. System 400 may also include controller 140 and sensors 180, 182,184 such as discussed above for system 100. Engine 402 includes anintake manifold 404 and an exhaust manifold 406. Exhaust manifold 406 isconnected to an exhaust system 408, and intake manifold 404 is connectedto an intake system 410. An EGR system 412 connects exhaust system 408with intake system 410 to provide an EGR flow. An EGR pump 414 in EGRsystem 412 can be operated to increase the pressure in intake manifold404.

Optionally or additionally, intake system 410 may include an electriccompressor 416 that is operable to increase a pressure in intakemanifold 404. Optionally or additionally, intake system 410 may beconnected to an inlet valve 418, such as may be associated with a brakesystem, that is operable to bleed air from the brake system or otherlocation into the intake system to increase a pressure in intakemanifold 404. Optionally or additionally, system 400 may include amultiple stage turbocharger 420 with a high pressure turbo 422 and a lowpressure turbo 424. A bypass 426 may be provided around low pressureturbo 424 that can be selectively opened to increase the intake manifoldpressure in intake manifold 404.

Certain systems are described following, and include examples ofcontroller operations in various contexts of the present disclosure. Theoperation of the engine 402, valve operating mechanism 170, and one ormore of EGR pump 414, electric compressor 416, inlet valve 418, andbypass 426 is controlled by the controller 140 in response to engineoperating conditions sensed by the sensors represented by sensor(s) 180,182, 184. In certain embodiments, the controller 140 interprets ordetermines a cylinder pressure of one or more cylinders 108 is less thana crankcase pressure of engine 402, and in response thereto commands oneor means to increase the intake manifold pressure. In an embodiment, themeans to increase the intake manifold pressure includes one or moredevices that are operable to increase the intake manifold pressure, suchas EGR pump 414, electric compressor 416, inlet valve 418, and/or bypass426.

Referring now to FIG. 5, there is shown a procedure 500 for operatingsystem 400. Procedure 500 includes a conditional 502 to determine if thepressure in one or more cylinders 108 at bottom dead center of piston150 is less than a crankcase pressure of engine 402. In order to makethis determination, procedure 500 includes an operation 504 to detect,estimate, or sense the crankcase pressure, such as with sensor 182.Procedure 500 also includes an operation 506 to make a prediction of thepressure in cylinder 108 at bottom dead center of the piston 150. Thedeterminations from operations 504 and 506 are input to conditional 502to make the determination of conditional 502. In one embodiment,operation 506 includes three different inputs to determine theprediction or estimate of cylinder pressure at bottom dead center ofpiston 150 during the intake stoke of piston 150, such as inputs 308,310, 312 discussed above for procedure 300.

Returning to conditional 502, if the cylinder pressure at bottom deadcenter of piston 150 is not less than the crankcase pressure of engine102, then conditional 502 is NO and an oil consumption issue is notpresent. Procedure 500 continues to monitor crankcase pressure andin-cylinder pressure at bottom dead center. If conditional 502 is YES,then procedure 500 continues at operation 514 to increase the pressureat intake manifold 110, which will prevent or reduce oil blow by fromthe crankcase into the combustion chambers of cylinders 108. Theoperation 514 may include, for example, operating one or more of EGRpump 414, electric compressor 416, inlet valve 418, and bypass 426 toincrease the intake manifold pressure at intake manifold 404.

Various aspects of the present disclosure are contemplated as indicatedin the present disclosure. According to one aspect, a system includes aninternal combustion including an intake manifold and a plurality ofcylinders. Each of the cylinders includes at least one intake valve andat least one exhaust valve. The system includes a VGT for receiving anexhaust flow from the plurality of cylinders and a controller operablyconnected with the VGT. The controller is configured to determine acrankcase pressure, determine a cylinder pressure of at least onecylinder associated with an early intake valve closing event, and, inresponse to the cylinder pressure being less than the crankcasepressure, the VGT is used to increase intake manifold pressure.

In one embodiment, the crankcase pressure is determined by one ofdetecting, sensing, or estimating the crankcase pressure. In oneembodiment, the cylinder pressure is determined at bottom dead center ofa piston of the at least one cylinder.

In one embodiment, the cylinder pressure is determined by predicting thecylinder pressure at bottom dead center of a piston of the at least onecylinder. In one embodiment, the prediction is based on an intake valveclosing angle, a volume change in the cylinder between the early intakevalve closing and bottom dead center of a piston of the at least onecylinder, and the intake manifold pressure. In one embodiment, theintake manifold pressure is determined by one of sensing, detecting, orestimating the intake manifold pressure.

In one embodiment, the intake manifold pressure is increased by closingthe VGT. In one embodiment, the intake manifold pressure is increased byopening the VGT.

In another aspect, a method for operating an internal combustion engineincludes determining a crankcase pressure associated with operation ofan internal combustion engine including a plurality of cylinders eachincluding at least one intake valve and at least one exhaust valve;determining a pressure in at least one cylinder at bottom dead center ofa piston in the at least one cylinder; and, in response to the pressurein the at least one cylinder being less than the crankcase pressure,controlling a VGT to increase an intake manifold pressure.

In one embodiment, the VGT is operated or adjusted by closing the VGT toincrease intake manifold pressure. In one embodiment, the VGT iscontrolled or adjusted by opening the VGT to increase intake manifoldpressure.

In one embodiment, determining the pressure in the at least one cylinderincluding predicting the pressure in the at least one cylinder. In oneembodiment, the pressure is predicted in response to an intake valveclosing angle, a volume change in the at least one cylinder between theintake valve closing and bottom dead center, and the intake manifoldpressure.

In another aspect, an apparatus includes a controller operable tocontrol operation of a plurality of cylinders of an internal combustionengine and a VGT. The controller is configured to determine a crankcasepressure of the internal combustion engine, determine a pressure in atleast one cylinder at bottom dead center of a piston in the at least onecylinder, and, in response to the pressure in the at least one cylinderbeing less than the crankcase pressure, operate the VGT to increase anintake manifold pressure of the internal combustion engine.

In an embodiment, the crankcase pressure is determined by one ofdetecting, sensing, or estimating the crankcase pressure. In anembodiment, the cylinder pressure is determined by predicting thecylinder pressure at bottom dead center of the piston of the at leastone cylinder. In an embodiment, the prediction is based on an intakevalve closing angle, a volume change between the early intake valveclosing and bottom dead center, and the intake manifold pressure. In anembodiment, the intake manifold pressure is determined by one ofsensing, detecting, or estimating the intake manifold pressure.

In one embodiment, the controller is configured to operate or adjust theVGT by closing the VGT. In one embodiment, the controller is configuredto operate or adjust the VGT by opening the VGT.

In another aspect, a system includes an internal combustion including anintake manifold and a plurality of cylinders. Each of the cylindersincludes at least one intake valve and at least one exhaust valve. Thesystem includes an intake system for providing a charge flow to theplurality of cylinders and an exhaust system for receiving an exhaustflow from the plurality of cylinders. The system also includes one ormore devices for increasing a pressure in the intake manifold. Thesystem further includes a controller operably connected with the meansfor increasing the pressure in the intake manifold. The controller isconfigured to determine a crankcase pressure; determine a cylinderpressure of at least one cylinder associated with an early intake valveclosing event; and in response to the cylinder pressure being less thanthe crankcase pressure, increase intake manifold pressure with the oneor more devices operable to increase the intake manifold pressure.

In one embodiment, the crankcase pressure is determined by one ofdetecting, sensing, or estimating the crankcase pressure. In oneembodiment, the cylinder pressure is determined at bottom dead center ofa piston of the at least one cylinder.

In one embodiment, the cylinder pressure is determined by predicting thecylinder pressure at bottom dead center of a piston of the at least onecylinder. In one embodiment, the prediction is based on an intake valveclosing angle, a volume change in the cylinder between the early intakevalve closing and bottom dead center of a piston of the at least onecylinder, and the intake manifold pressure. In one embodiment, theintake manifold pressure is determined by one of sensing, detecting, orestimating the intake manifold pressure.

In one embodiment, the device for increasing the intake manifoldpressure includes an EGR pump in an EGR system that connects the exhaustsystem to the intake system. In one embodiment, the device forincreasing the intake manifold pressure includes an electric compressorconnected to the intake system to compress the charge flow. In oneembodiment, the device for increasing the intake manifold pressure aturbine bypass. In one embodiment, the device includes an intake airinlet valve.

In one aspect, a method for operating an internal combustion engineincludes: determining a crankcase pressure associated with operation ofan internal combustion engine including a plurality of cylinders eachincluding at least one intake valve and at least one exhaust valve;determining a pressure in at least one cylinder at bottom dead center ofa piston in the at least one cylinder; and in response to the pressurein the at least one cylinder being less than the crankcase pressure,increasing an intake manifold pressure.

In one embodiment, increasing the intake manifold pressure includesoperating an EGR pump in an EGR system that connects an exhaust systemwith the intake manifold. In one embodiment, increasing the intakemanifold pressure includes operating an electric compressor in an intakesystem connected to the intake manifold. In one embodiment, increasingthe intake manifold pressure includes providing air into an intakesystem connected to the intake manifold. In one embodiment, increasingthe intake manifold pressure includes bypassing a low pressure turbinein a multiple stage turbocharger system.

In one embodiment, determining the pressure in the at least one cylinderincluding predicting the pressure in the at least one cylinder. In arefinement of this embodiment, the pressure is predicted in response toan intake valve closing angle, a volume change in the at least onecylinder between the intake valve closing and bottom dead center, andthe intake manifold pressure.

In another aspect, an apparatus includes a controller operable tocontrol operation of a plurality of cylinders of an internal combustionengine and a means for increasing a pressure in an intake manifold ofthe internal combustion engine. The controller is configured todetermine a crankcase pressure of the internal combustion engine anddetermine a pressure in at least one cylinder at bottom dead center of apiston in the at least one cylinder. In response to the pressure in theat least one cylinder being less than the crankcase pressure, thecontroller is configured to operate the pressure increasing means toincrease the pressure of the intake manifold.

In one embodiment, the pressure increasing means is an EGR pump in anEGR system of the internal combustion engine. In one embodiment, thepressure increasing means is an electric compressor in an intake systemof the internal combustion engine. In one embodiment, the pressureincreasing means includes at least one of a turbine bypass and an intakeair inlet valve.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly certain exemplary embodiments have been shown and described. Thoseskilled in the art will appreciate that many modifications are possiblein the example embodiments without materially departing from thisinvention. Accordingly, all such modifications are intended to beincluded within the scope of this disclosure as defined in the followingclaims.

In reading the claims, it is intended that when words such as “a,” “an,”“at least one,” or “at least one portion” are used there is no intentionto limit the claim to only one item unless specifically stated to thecontrary in the claim. When the language “at least a portion” and/or “aportion” is used the item can include a portion and/or the entire itemunless specifically stated to the contrary.

What is claimed is:
 1. A system comprising: an internal combustionincluding an intake manifold and a plurality of cylinders, each of thecylinders including at least one intake valve and at least one exhaustvalve; an intake system for providing a charge flow to the plurality ofcylinders; an exhaust system for receiving an exhaust flow from theplurality of cylinders; one or more devices for increasing a pressure inthe intake manifold; and a controller operably connected with the one ormore device, wherein the controller is configured to: determine acrankcase pressure; determine a cylinder pressure of at least onecylinder associated with an early intake valve closing event; and inresponse to the cylinder pressure being less than the crankcasepressure, increase intake manifold pressure by operating the one or moredevices.
 2. The system of claim 1, wherein the crankcase pressure isdetermined by one of detecting, sensing, or estimating the crankcasepressure.
 3. The system of claim 1, wherein the cylinder pressure isdetermined at bottom dead center of a piston of the at least onecylinder.
 4. The system of claim 1, wherein the cylinder pressure isdetermined by predicting the cylinder pressure at bottom dead center ofa piston of the at least one cylinder.
 5. The system of claim 4, whereinthe prediction is based on an intake valve closing angle, a volumechange in the cylinder between the early intake valve closing and bottomdead center of a piston of the at least one cylinder, and the intakemanifold pressure.
 6. The system of claim 5, wherein the intake manifoldpressure is determined by one of sensing, detecting, or estimating theintake manifold pressure.
 7. The system of claim 1, wherein the one ormore devices includes an exhaust gas recirculation (EGR) pump in an EGRsystem that connects the exhaust system to the intake system.
 8. Thesystem of claim 1, wherein the one or more devices includes an electriccompressor connected to the intake system to compress the charge flow.9. The system of claim 1, wherein the one or more devices includes atleast one of a turbine bypass and an intake air inlet valve.
 10. Amethod for operating an internal combustion engine, comprising:determining, with a controller, a crankcase pressure associated withoperation of an internal combustion engine including a plurality ofcylinders each including at least one intake valve and at least oneexhaust valve; determining, with the controller, a pressure in at leastone cylinder at bottom dead center of a piston in the at least onecylinder; and in response to the pressure in the at least one cylinderbeing less than the crankcase pressure and in response to one or morecommands from the controller, increasing an intake manifold pressure.11. The method of claim 10, wherein increasing the intake manifoldpressure includes operating an exhaust gas recirculation (EGR) pump inan EGR system that connects an exhaust system with the intake manifold.12. The method of claim 10, wherein increasing the intake manifoldpressure includes operating an electric compressor in an intake systemconnected to the intake manifold.
 13. The method of claim 10, whereinincreasing the intake manifold pressure includes providing air into anintake system connected to the intake manifold.
 14. The method of claim10, wherein increasing the intake manifold pressure includes bypassing alow pressure turbine in a multiple stage turbocharger system.
 15. Themethod of claim 10, wherein determining the pressure in the at least onecylinder includes predicting the pressure in the at least one cylinder.16. The method of claim 15, wherein the pressure is predicted inresponse to an intake valve closing angle, a volume change in the atleast one cylinder between the intake valve closing and bottom deadcenter, and the intake manifold pressure.
 17. An apparatus, comprising:a controller operable to control operation of a plurality of cylindersof an internal combustion engine and a means for increasing a pressurein an intake manifold of the internal combustion engine, wherein thecontroller includes a non-transitory computer-readable medium withinstructions stored thereon, that when executed by a processor, performthe steps comprising: determining a crankcase pressure of the internalcombustion engine; determining a pressure in at least one cylinder atbottom dead center of a piston in the at least one cylinder; and inresponse to the pressure in the at least one cylinder being less thanthe crankcase pressure, operating the pressure increasing means toincrease the pressure of the intake manifold.
 18. The apparatus of claim17, wherein the pressure increasing means is an exhaust gasrecirculation (EGR) pump in an EGR system of the internal combustionengine.
 19. The apparatus of claim 17, wherein the pressure increasingmeans is an electric compressor in an intake system of the internalcombustion engine.
 20. The apparatus of claim 17, wherein the pressureincreasing means includes at least one of a turbine bypass and an intakeair inlet valve.